MARBELLA, Spain The suspected mastermind behind a failed bid to steal hundreds of millions of dollars in diamonds from London's Millennium Dome has been arrested in southern Spain, AFP reported on Monday.

The 46-year-old British national was arrested Friday by Spanish police in the presence of British detectives at a villa near the resort city of Marbella on the Costa del Sol, police said.

They declined to identify the suspect or give further details of the arrest pending his appearance before a judge. British media identified the suspect as James Hurley.

He is sought by British police on charges that he planned the failed assault in November on a collection of De Beers diamonds on display at the millennium dome, including the 203-carat millennium star worth an estimated $500 million.

British police learned of the planned robbery, replaced the diamonds with fakes and set a trap for the thiefs, arresting four men as they used a bulldozer to burst into the gigantic dome.

Two other people were arrested in a getaway speedboat on the river Thames and five more were detained in subsequent raids in southern England.